Aside from the usage screen (available by typing 'xv -help' at the command line), documentation for XV is now distributed only as a PostScript (or PDF) file, as it has gotten enormous and is no longer very well suited to the 'man' page format. Print a copy of the (100-ish page) manual found in docs/xvdocs.ps. If you are unable to get the manual to print on your printer, you may purchase a printed copy of the XV manual. Click on 'About XV' in the program to get further information.
If you don't have the PostScript file, it is part of the standard XV distribution, the latest version of which can be obtained from http://www.trilon.com/xv/ or via anonymous ftp from ftp.cis.upenn.edu in the directory pub/xv .
This version has been patched with the XV Jumbo Patches, available from http://pobox.com/~newt/greg_xv.html.